The invention relates to a socket for a miniature incandescent lamp for the detachable and lockable insertion in a recess in a printed circuit board and for making electrical contact with the lamp by pressing the connecting leads against the printed circuit board with a separate manufacture of the socket and the lamp.
Such a socket is already known from U.S. Pat. No. 4,193,653. For this embodiment, the socket consists of a single part, through which the connecting leads of the lamp are passed. In the lower part of the socket, the leads form a loop in a guide in a flange. When the socket is inserted, the flange presses the connecting leads, which emerge at its upper side, against the underside of the printed circuit board.
This principle of making electrical contact between the connecting leads of the lamp and the printed circuit board has several advantages over constructions with integrated contact elements of metal or a conductive plastic, to which the connecting leads of the lamp are soldered, welded, riveted, wedged, glued, integrally molded or pressed. The socket can be produced in a single operation, because it consists of only a single plastic part. Since the glass bulb is not subjected to stresses either by temperature or by pressure during the insertion of the lamp, the material properties of the glass lamp are of no significance and the socket is suitable for all lamps of appropriate construction.
The manufacture of the socket of U.S. Pat. No. 4,193,653 is uncomplicated. However, the insertion of the lamp in the socket creates considerable difficulties. For this purpose, the lamp with the connecting leads aligned in parallel must first of all be brought into the socket, so that the connecting leads pass through an opening for each in the bottom of the socket. Subsequently, each connecting lead is threaded at least twice more through recesses provided for this purpose in a flange in the base. The fact that the connecting leads of the lamp generally are very thin and are easily bent if they are not introduced without making contact, is particularly disadvantageous. Inserting the lamp in the socket by hand is therefore unreasonable, even in the case of small numbers. It is therefore out of the question to sell the lamp and the socket separately. Instead, the lamp must be offered with the socket as a finished unit. Moreover, the insertion of the lamp in the socket requires complicated, precision and therefore expensive machines.